While it's unsurprising that something sad or happy happening to a large number of close friends and acquaintances can affect our emotions, the study does offer a modicum of proof social media is affecting the mood of users, for better our worse.

The authors wrote: "In an experiment with people who use Facebook, we test whether emotional contagion occurs outside of in-person interaction between individuals by reducing the amount of emotional content in the News Feed. When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred."

Guinea pigs

Naturally, as Gizmodo points out, the machine-based testing is all covered under Facebook's privacy policy.

"We show, via a massive (N = 689,003) experiment on Facebook, that emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness," the study claimed.